Effect of long-term fertilization on C mineralization and production of CH4 and CO2 under anaerobic incubation from bulk samples and particle size fractions of a typical paddy soil

Impacts of nutrient management on C mineralization and greenhouse gas (GHGs) emission from soils have been of much concern in global change. Using laboratory incubation, the production of CH₄ and CO₂ were studied from both bulk samples and the particle size fractions (PSF) of topsoil from a paddy under a long-term different fertilization trial (including non (NF), chemical without (CF) and with manure (CFM) fertilization, respectively) in the Tai Lake Region, China. Four PSFs (2000–200, 200–20, 20–2, <2 μm) were separated from undisturbed samples collected after rice harvest by a low-energy ultrasonic dispersion procedure. Both the bulk samples and PSFs were incubated under submerged condition for 72 days. The concentration of CH₄ and CO₂ evolved during incubation were determined by gas chromatography. C mineralization rates ranged from 0.13 to 0.52 mg C g⁻¹ C day⁻¹, with different fertilizations and size of the PSFs, and were not correlated with C/N ratio. While CO₂ production predominated over CH₄ from C mineralization from both bulk samples and the size fractions, CH₄ production played a predominant role in the total global warming potential (GWP) under all treatments. C mineralization of bulk soil was significantly higher under CF than under CFM and NF. CH₄ production, however, was 3 times as under CFM and 27 times as under NF, indicating a tremendous effect of chemical fertilization alone on the total GWP. CO₂ production from the PSFs differed from CH₄ under a single treatment, which was notably from the coarse PSFs larger than 200 μm. Higher C mineralization and CH₄ production with a higher metabolic quotient under CF implicated a vulnerability of soil functioning of GHGs mitigation in the paddy receiving chemical fertilizers only. Thus, rational organic amendments should be undertaken for mitigating the climate change.     

甲磺隆在土壤腐殖物质中结合残留的动态变化

土壤中14 C 甲磺隆的可提取态残留物随时间延长不断降低 ,而其结合态残留率第 2 8天达最高 .14 C 甲磺隆结合态残留物在土壤腐殖物质中的分布是 :富啡酸 胡敏素 >胡敏酸 .在处理最初 2 8天 ,富啡酸中14 C 甲磺隆结合态残留物不断增大 ,随后减少 ;胡敏素中的结合态残留量在 2 8— 2 2 4天变化不大 .14 C残留物在不同土壤之间的结合及其分布都是有差异的 ,与土壤pH值、粘粒矿物类型等都有密切关系     

某超临界汽轮机主汽阀杆断裂原因分析

目的 某热电厂超临界机组汽轮机发生主蒸汽阀阀杆(标称材质为22Cr12NiMoWV(C422)钢)断裂事故,对发电安全造成不良影响.为此,分析该阀杆断裂失效的原因,提出改进措施,以避免类似事故的发生.方法 从外观检查、成分测定、金相检验以及断口观察等方面入手,结合硬度和冲击性能测试,探讨阀杆断裂的主要原因.结果 该断裂...     

秸秆与氮肥配比对农田土壤内外源碳释放的影响

秸秆配施氮肥调节C/N 比不仅影响外源秸秆的矿化,也影响内源土壤有机碳(SOC)的分解(即激发效应),因此研究秸秆与氮肥配比对土壤内外源有机碳分解的影响,对于农田温室气体减排和土壤肥力提升具有双重意义.本研究以山东桓台农田土壤为研究对象,为了探究秸秆与氮肥的配比对秸秆与SOC 分解的影响,在不同氮肥水平下,采用13C ...     

Recent advances in special morphologic photocatalysts for NOx removal

Content>● Systematic information of recent progress in photocatalytic NO _x removal is provided.Content> Content>● The photocatalysts with special morphologies are reviewed and discussed.Content> Content>● The morphology and photocatalytic NO _x removal performance is related.Content> The significant increase of NO_x concentration causes severe damages to environment and human health. Light-driven photocatalytic technique affords an ideal solution for the removal of NO_x at ambient conditions. To enhance the performance of NO_x removal, 1D, 2D and 3D photocatalysts have been constructed as the light absorption and the separation of charge carriers can be manipulated through controlling the morphology of the photocatalyst. Related works mainly focused on the construction and modification of special morphologic photocatalyst, including element doping, heterostructure constructing, crystal facet exposing, defect sites introducing and so on. Moreover, the excellent performance of the photocatalytic NO_x removal creates great awareness of the application, which has promising practical applications in NO_x removal by paint (removing NO_x indoor and outdoor) and pavement (degrading vehicle exhausts). For these considerations, recent advances in special morphologic photocatalysts for NO_x removal was summarized and commented in this review. The purpose is to provide insights into understanding the relationship between morphology and photocatalytic performance, meanwhile, to promote the application of photocatalytic technology in NO_x degradation.     

气水比对A/O-BF处理低碳氮比农村生活污水脱氮的影响

为揭示好氧段气水比对缺氧/好氧生物滤池(Anoxic/Oxic Biofilter,A/O-BF)脱氮的影响机理,采用A/O-BF处理低碳氮比农村生活污水,结合实时荧光定量聚合酶链式反应技术,对比研究了好氧段气水比为4∶1、2∶1和1∶1时A/O-BF的脱氮效能和微生物群落变化特征.结果表明:当气水比为4∶1时,A/O...